Reply to Letter to the Editor: The Withdrawn ASR™ THA and Hip Resurfacing Systems: How Have Our Patients Fared Over 1 to 6 Years?

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We thank Drs. Amstutz and Le Duff for their thoughtful letter regarding our study [1]. Specifically, they take issue with our Discussion section and the statement regarding the performance of metal-on-metal (MOM) devices as a class. I suspect they would agree that when taken as a class and grouped together as MOM devices they do not perform as favorably as the metal-on-polymer devices in the registry data. Their point is well taken that it likely is not fair to group all of the MOM devices in this fashion as the different devices have varied results reported in the literature. Some devices have fared better and functioned well in many patients. However, we believe the articular surface replacement (ASR™) device is not the only one with failure issues and therefore this class of devices needs further scrutiny and followup. The unanticipated mechanisms of failure in metal devices related to unintended edge loading and corrosion are real and the class of devices needs to be monitored. …